“The event … turned out to be one of the most moving evenings I’ve ever had,” the pop singer and actor wrote in a blog post on his website after attending the Nov. 12 event.

Marine Corps Cpl. Kelsey De Santis invited Timberlake to her unit’s ball this summer via YouTube. She jokingly told him that if he couldn’t attend, “All I have to say is, cry me a river!” – a reference to Timberlake’s hit single.

Timberlake said he felt flattered by the invitation and went into the evening knowing he “would have an evening that I wouldn’t forget” to share with his friends.

“What I didn’t know was how moved I would be by the whole experience,” he wrote.

Timberlake had special words for his date, who he said went out of her way to ensure he enjoyed himself. “I have to tell you, it’s not every day that I meet a 23-year old girl and she’s more worried about if I’m having fun or if I’m comfortable,” he wrote.

He said he loved meeting De Santis’ friends, and felt an immediate connection with them.

“It hit me all of a sudden that these were the type of people that look after us and our freedom -- humble, concerned for others before themselves,” he wrote. “This was the type of person our Marine Corps was building. I was really blown away.”

Timberlake said he’s been lucky to have met many of his heroes, from Michael Jordon to Michael Jackson.

“And, nothing makes me feel more honor and pride than when I get to meet one of you,” he wrote in his blog to the men and women in uniform.

“Last night changed my life and I will never forget it,” he wrote. “Thank you, Corporal Kelsey De Santis. Thank you for inviting me. And, thank you for being my hero.”

De Santis has been making the media rounds, sharing her impressions of her date with Timberlake.

She said she was particularly struck by his reaction to a video played during the ball that showed historic events that drew the Marine Corps into action, including Pearl Harbor, World War II and the Sept. 11 attacks.

“Right after the ceremony, we kind of locked eyes and we were both grateful for the things our country stands for and just everything that our military has done for us,” De Santis told ABC’s “Good Morning America” yesterday.

It was reflected, she said, “not only in the look on his face, but also the look on everyone else’s face and the feeling in the entire room.”